Radiative lifetimes and alignment depolarization cross sections for YbI and II by the Hanle effect in a flowing helium system

The radiative lifetimes of the 17992-,25068-,28857-, 37414-, 40564-, and 44017-cm^-1 neutral levels and the 30392-cm^-1 ion level of Yb have been measured by the Hanle method in a fast-flowing He system. The lifetimes (in units of 10^-9 sec) were found to be 820(20), 5.12(0.12), 14.4(0.4), 77.4(6.0), 9.32(0.6), 39.1(3.5), and 5.8(0.6), respectively. In a flowing system with He as a buffer gas the alignment depolarization cross sections with Yb were obtained and are reported here for the first time. They are (in units of 10^-15 cm²) 5.0(1.0), 5.9(1.0), 5.9(1.2), 17.9(2.0), 28.2(3.0), 5.16(4.0), and 7.2(2.5), respectively.